Unlike aircraft that fly using the principles of dynamic lift, lighter than air vehicles, or “aerostats”, use lighter than air gases for buoyancy.
Lighter than air vehicles tend to be capable of maintaining altitude for long periods because no, or little, fuel is expended to maintain lift. However, the time that they can spend airborne is limited.
Lighter than air vehicles are typically situated from 300 m to 30 km altitude.
Lighter than air vehicles are used for a wide variety of applications, such as telecommunications, positioning, and observation applications. Example applications for lighter than air vehicles include the provision of high speed internet, e-mail, telephony, televisual services, backhaul services, video-on-demand, global positioning, astronomical observations, atmospheric monitoring, and aerial photography.